Speed-setting indicators for portable electric tools



April 9, 1963 G. J. ABEL 3,085,169

SPEED-SETTING INDICATORS FOR PORTABLE ELECTRIC TOOLS Filed Feb. 24, 1960IN VENT OR, GEORGE J. ABEL.

BY. 7 I ziTTomm atent Patented Apr. 9, 1963 Free ' 3,085,169SPEED-SETTING INDICATORS FOR PORTABLE ELECTRIC TOOLS George J. Abel,Plainfield, N.J., assignor to Diehl Manufacturing Company, Somerville,N.J., a corporation of New Jersey Filed Feb. 24, 1960, Ser. No. 10,681 3Claims. (Cl. 31068) This invention relates to speed-setting indicatorsfor portable electric tools adapted to be used with cutters of varioussizes for cutting different materials.

It is known that for each material and cutter size there exists anoptimum speed for most eflicient removal of material. In a prior UnitedStates patent application Serial No. 215, filed January 4, 1960, abuilt-in speed regulating control system for a portable electric drillis described in which optimum speeds may be set by dialing a specificdrill size for a single material. It is desirable to extend this speedsettability to other materials ordinarily encountered and the presentinvention relates to means for its accomplishment.

It is an object of this invention to provide a speedsetting indicatorfor a portable electric tool having a speed-regulating control systemwhereby optimum cutting speeds for different cutter sizes and differentmaterials may be conveniently preset.

With the above and other objects in view, as will hereinafter appear,the invention comprises the devices, combinations and arrangements ofparts hereinafter set forth and illustrated in the accompanying drawingsof a preferred embodiment of the invention, from which the sev eralfeatures of the invention and the advantages attained thereby, will bereadily understood by those skilled in the art.

In the drawings,

FIG. 1 is a side elevational view of a portable electric tool having aportion cut away to show a speed-setting element embodying theinvention.

FIG. 2 is an enlarged plan view of the speed-setting indicator shown inFIG. 1.

FIG. 3 is a vertical sectional view, partly in elevation, taken on theline 33 of FIG. 2.

FIG. 4 is a plan view, partly in section, taken on the line 44 of FIG.3.

FIG. 5 is a plan view, partly in section, taken on the line 55 of FIG.3.

Referring to the drawings, FIG. 1 shows a portable electric drill havinga built-in speed regulating control system of the type shown anddescribed in the United States patent application Serial No. 215, filedJanuary 4, 1960. It is sufficient for the purposes of this invention topoint out that 11 designates the speed-setting potentiometer resistanceas shown in the reference structure.

The potentiometer 11 is mounted on the handle portion 12 of the drill1t) and is secured thereon by a nut 13 threaded onto a stud portion 14,as seen best in FIG. 3.

A knob 15 is secured to the potentiometer shaft 16 by means of aset-screw 17 and provides means for manually adjusting the setting ofthe potentiometer 11 and thus for controlling the cutter speedcorresponding thereto.

A rotatable index disc 18 is formed with a central circular aperturedportion 19 which engages a raised boss 20 formed on the handle portion12 to provide a bearing structure therefor and thus to confine itsmovement to a rotary one about the axis of the shaft 16.

A cup 21 pressed into the wall of the handle portion contains acompression spring 22 and a ball 23 urged out of said cup but retainedtherein by a spun-over edge 24 of the cup. The ball 23 cooperates withdepressions 25 made in the under face of the index disc 18 to provide adetent for indexing said disc to several predetermined angularpositions. To limit the rotation of disc 18 to a practical range, stoppins 26 screwed into the disc 18 cooperate with arcuate slots 27 in thehandle portion 12, as seen best in FIG. 4.

A stationary index mark 28 on the handle portion 12 cooperates withindicia 29 in the form of depressed dots on the index disc 18corresponding to the material (plastic, wood, steel) to be cut, toprovide a movable index means for the knob 15 to effect recalibration ofthe potentiometer in accordance with the different materials selected.Indicia 30 in the form of depressed dots corresponding to cutter size(in this case drill bit diameters) cooperate With an index mark 31 onthe knob 15 to provide means for setting the potentiometer to correspondto a predetermined optimum speed for the material and cutter size soselected.

It will be understood that matched color coding may be used tofacilitate convenience in use, in which case index mark 28 and indicia29 are made in one color while index 31 and indicia 30 are made inanother distinctly different color.

While the invention has been described herein as applied to portableelectric drills it is not to be construed as so limited thereto but canreadily be adapted to any portable electric tool wherein twopredetermined variables have a direct influence on the optimum operatingspeed for the conditions imposed. Other possible applications, forexample, are for a sabre saw and a belt sander. In these cases onevariable would be the material to be sawed or sanded and the secondvariable would be the coarseness of the blade (teeth per inch) and thecoarseness of the sandling belt, respectively,

Having thus set forth the nature of the invention, what I claim hereinis:

1. An adjustable speed-setting element for a portable electric toolhaving attachable cutter elements of various sizes, a commutator motorhaving series-connected field and armature windings and aspeed-regulating control system for said motor, comprising knob andpointer means for adjusting said element, and a normally stationaryindex plate carrying indicia of material kind and cutter sizecooperating with said knob and pointer means for adjusting saidspeed-setting element to a predetermined optimum speed corresponding toa selected material kind and cutter size, said index plate being movableselectively with respect to said speed-setting element to effectrecalibration thereof in accordance with the kind of material to be cut.

2. An adjustable speed-setting element for a portable electric toolhaving attachable cutter elements of various sizes, a driving electricmotor therefor and a speed-regulating system for said motor, comprisingmeans for adjusting said speed-setting element including a knob, anormally stationary index plate, means for indexing said knob relativelyto said plate and means for angularly moving said index plate relativelyto a stationary index in accordance with the kind of material to be cut.

3. A speed-setting indicator for a portable electric tool having aspeed-regulating control system comprising a 3 4 spiedsetting element, ashaft for adjusting the element, References Cited in the file of thispatent a nob secured to said shaft, an index plate selectively rotatableabout the axis of said shaft, first indicia carried UNITED STATESPATENTS by said index plate corresponding to kind of material 1,522,634Klosner Jan. 13, 1925 and second indicia carried by said index platecorrespond- 5 1,536,710 Greene May 5, 1925 ing to cutter size,stationary marker means cooperating 2,671,191 Braski Mar. 2, 1954 Withsaid first indicia for indexing said index plate in ac- 2,707,222 Brownet a1 Apr. 26, 1955 cordance with the kind of material to be cut, andmarker 2,711,461 Happe June 21, 1955 means on said knob cooperating withsaid second indicia 2,857,533 Miller Oct. 21, 1958 for indexing saidknob in accordance With the cutter size. 10 2,939,064 Momberg et a1. May31, 1960

1. AN ADJUSTABLE SPEED-SETTING ELEMENT FOR A PORTABLE ELECTRIC TOOLHAVING ATTACHABLE CUTTER ELEMENTS OF VARIOUS SIZES, A COMMUTATOR MOTORHAVING SERIES-CONNECTED FIELD AND ARMATURE WINDINGS AND ASPEED-REGULATING CONTROL SYSTEM FOR SAID MOTOR, COMPRISING KNOB ANDPOINTER MEANS FOR ADJUSTING SAID ELEMENT, AND A NORMALLY STATIONARYINDEX PLATE CARRYING INDICIA OF MATERIAL KIND AND CUTTER SIZECOOPERATING WITH SAID KNOB AND POINTER MEANS FOR ADJUSTING SAIDSPEED-SETTING ELEMENT TO A PREDETERMINED OPTIMUM SPEED CORRESPONDING TOA SELECTED MATERIAL KIND AND CUTTER SIZE, SAID INDEX PLATE BEING MOVABLESELECTIVELY WITH RESPECT TO SAID SPEED-SETTING ELEMENT TO EFFECTRECALIBRATION THEREOF IN ACCORDANCE WITH THE KIND OF MATERIAL TO BE CUT.